Tag: laser selective soldering machine

Spark-400 is a laser-based automated selective soldering machine for SMT line. The automated selective assembly and rework system addresses some of the key technical issues and concerns of PCB assembly and rework.

Concern-1: Selective assembly of through-hole components such as sockets and connectors. These problems are going to remain as long as through-hole components will remain in the SMT industry. Remember, not all electronic components are available as SMD (Surface Mount Device).

In a mixed PCB assembly, through-hole components are soldered selectively by three methods:

Wave soldering using a specially designed fixture

Paste-in-hole process

Hand soldering.

When selective wave soldering and paste-in-hole process are not technically feasible, hand soldering using soldering station or iron is used as the last option. Hand soldering is slow, expensive and operator-dependent, resulting in inconsistent solder joints. Hand soldiering is susceptible to external and internal damage leading to unreliable PCB Assembly even after passing electrical tests.

Concern-2: Through-hole components are not just the reason behind selective soldering. Another reason for automated selective soldering is increasing use of selective RF shield soldering, such as in mobile cell phones. While some of these RF shields can be reflow soldered in convection ovens, many of them still need to be soldered by hand. Even shields that can be soldered in convection ovens require hand soldering for removal to allow rework of components shielded by them. Additionally, there are many surface mount connectors, especially those with leads on each side of the board that need to be selectively soldered.

Concern-3: Moisture-sensitive devices must be baked before soldering to prevent package cracking, commonly referred to as popcorning. Reworking an expensive device can be painful and very expensive. In conventional methods, to rework an individual component, the entire PCB assembly must be baked for 24 hours to seven days. This increases chances of potential damage to the board, especially while removing large components such as fine pitch, plastic leaded chip carriers (PLCC), ball grid arrays (BGA) and small components such as chip scale packages (CSP). This problem gets worse with use of lead-free solder that have a high melting points compared to leaded solder.

Spark-400 automated lased-based selective soldering machine is perfect solution to all these concerns. This laser assembly machine has the ability to selectively assemble any component thus addressing these technical concerns. It is a laser soldering and assembly machine that can perform all the assembly functions from solder paste dispensing and flux application to inspection and rework. This machine dispenses solder paste with positive force displacement to accurately control paste volume. Various pick-up heads pick up components from as small as 0402 to as large as BGAs and fine pitch. Multiple diode lasers selectively or simultaneously solder in milliseconds. Because laser cannot see BGA, CSP and flip chip balls, the laser beam width is increased to simulate an oven profile to reflow hidden solder balls. The system can also perform rework and inspection functions. There is no need for programming because computer-aided design (CAD) data is used for all assembly functions – paste dispensing, placement, soldering and rework. Components such as fine pitch do not have to be baked because the package does not get hot, only the leads do.

Beamworks Spark-400 machine can be used for both high-volume and low-volume applications. For example, if it is used only as a soldering machine, multiple lasers can keep up with the high-volume pick-and-place machine in the line. It can also be used to selectively assemble components in a high-volume line. Examples include missing components in an already assembled board or an RF shield in a high-volume line. In low-volume applications, it can assemble all components in quick-turn applications.

While this machine can be used for low-volume, quick-turn applications, it is well suited for unique applications where conventional processes either are not technically feasible or are too expensive. Additionally, because reflow time for each joint can be individually programmed, the heat input for each joint can be precisely tailored to meet the needs of joints connected to power and ground planes or heat sinks. Because this machine measures soldering time in milliseconds (as opposed to seconds), the inter-metallic thickness is under 1 mm (or less than 40 m”. Compare this to 500 m” or more in other soldering methods), greatly improving solder joint reliability.

Spark 400 from BeamWorks is an automated selective assembly system that performs all functions of a typical SMT line – solder paste dispensing, component placement, laser soldering and inspection. Soldering and inspection functions are performed concurrently to provide real-time feedback on solder joint quality. This is one of its kind machine that automatically stops soldering when desired solder joint quality is achieved. It tailors heat input to a specific component as well as to a specific lead. If a certain lead of a given component is connected to power or ground plane, the laser soldering time is longer for that lead than the adjacent lead not connected to a heat sink.

Because the machine dispenses paste, a partially assembled board does not pose any problems as it would if a stencil were used. It does not require separate programming for dispensing, placement and soldering. Paste dispensing is done either as dots or a thin strip of paste. Then, using the same computer-aided design (CAD) data, it places components and quickly solders them using four diode lasers. During the process, the selective assembly of missing surface mount components does not affect in any way the components that already have been assembled on the conventional SMT line. Also, because the heat source for reflow is a diode laser, the moisture-sensitive components already assembled (or to be assembled) do not require baking.

Missing components have been one reason for quality and delivery problems in manufacturing. Using Spark-400 selective automated assembly system from BeamWorks provides a cost-effective system for addressing this common industry problem.